Metrics Not Emitted When Timeseries Has No Dimensions

[mshah07]

Bug: Metrics Not Emitted When Timeseries Has No Dimensions

Exporter Version:
v25.5.0

Azure Resource Type:
Microsoft.Network/virtualNetworkGateways

Example Metrics:

• TunnelIngressPackets
• TunnelEgressPackets

---

🐛 Problem

The exporter receives data from Azure Monitor (verified via az monitor metrics list), but the response contains no metadatavalues, i.e., no dimensions.
Despite valid data (non-zero totals), the exporter emits no Prometheus metrics — response is always 200 OK with Content-Length: 0.

---

✅ Repro Steps

1. Deployed azure-metrics-exporter with:

   args:
     - --server.bind=:9276
     - --metrics.template={name}

2. Verified Azure CLI returns valid metric data:

   az monitor metrics list \
     --resource <resourceId> \
     --metric TunnelIngressPackets \
     --aggregation Total

3. Probed the exporter:

   curl "http://localhost:9276/probe/metrics?aggregation=total&interval=PT5M&metric=TunnelIngressPackets&name=custom&resource=<full-resource-id>&resourceType=Microsoft.Network/virtualNetworkGateways&subscription=<subscription-id>&timespan=PT1H"

4. Exporter logs show request handled with status 200, but Prometheus output is empty.

5. Also tested:

   • Removing config.yaml
   • Using name=custom
   • Adding --metrics.template={name}

---

🤔 Expected Behavior

Exporter should emit flat Prometheus metrics even if Azure Monitor omits dimensions (metadatavalues[] is empty).

---

❌ Actual Behavior

Exporter silently skips these metrics. Only metrics with dimensions are emitted.

---

📎 Azure CLI Response Sample

"timeseries": [
  {
    "data": [
      {
        "timeStamp": "2025-05-08T11:14:00Z",
        "total": 64144.0
      }
    ],
    "metadatavalues": []
  }
]

[mblaschke]

Please check if you have a valid interval, otherweise the Azure Monitor REST API doesn't deliver any values.
Empty metadatavalues should not be a problem at all 🤔